Fence Post Spacing & Concrete Calculator

On-center post count and bagged concrete for a fence line — privacy, picket, chain-link, or field. Not a deck beam post calculator.

Enter fence type, height, and run. Optional preferred spacing is capped at the recommended max for wind. Hole diameter, depth, and a gravel bed size the concrete cylinder minus the post. This is fence-line layout, not IRC deck post spacing — that is a different tool: deck post spacing calculator. How the numbers work: spacing and concrete guide. Field failures: troubleshooting. Setting method: concrete vs gravel vs packed dirt. Other pours: concrete volume calculator. Carpentry index: hub.

Embed this calculator Free · no API key · keep the attribution link

Copy the snippet below to embed this calculator on your site. The attribution link must stay intact and dofollow (no rel="nofollow"). Browse all embeddable calculators

Theme Width

<div class="ttq-embed" style="max-width:100%;margin:0 auto;">
  <iframe src="https://testtalkhq.com/embed/fence-post-spacing-calculator/?theme=light&utm_source=embed" width="100%" height="980" frameborder="0" loading="lazy" scrolling="no" title="Fence Post Spacing & Concrete Calculator — TestTalkHQ" style="border:0;max-width:100%;width:100%;"></iframe>
  <p style="font:400 13px/1.4 system-ui,sans-serif;text-align:center;margin:6px 0 0;">Powered by the <a href="https://testtalkhq.com/fence-post-spacing-calculator/?utm_source=embed&utm_medium=referral&utm_campaign=calculator_embed&utm_content=fence-post-spacing-calculator" target="_blank" rel="noopener">Fence Post Spacing & Concrete Tool</a> from <a href="https://testtalkhq.com/?utm_source=embed&utm_medium=referral&utm_campaign=calculator_embed&utm_content=fence-post-spacing-calculator" target="_blank" rel="noopener">TestTalkHQ</a></p>
</div>

<div class="ttq-embed" style="max-width:100%;margin:0 auto;">
  <iframe src="https://testtalkhq.com/embed/fence-post-spacing-calculator/?theme=light&utm_source=embed" width="100%" height="980" frameborder="0" loading="lazy" scrolling="no" title="Fence Post Spacing & Concrete Calculator — TestTalkHQ" style="border:0;max-width:100%;width:100%;"></iframe>
  <p style="font:400 13px/1.4 system-ui,sans-serif;text-align:center;margin:6px 0 0;">Powered by the <a href="https://testtalkhq.com/fence-post-spacing-calculator/?utm_source=embed&utm_medium=referral&utm_campaign=calculator_embed&utm_content=fence-post-spacing-calculator" target="_blank" rel="noopener">Fence Post Spacing & Concrete Tool</a> from <a href="https://testtalkhq.com/?utm_source=embed&utm_medium=referral&utm_campaign=calculator_embed&utm_content=fence-post-spacing-calculator" target="_blank" rel="noopener">TestTalkHQ</a></p>
</div>
<script>(function(){function r(e){if(!e||!e.data||e.data.type!=="ttq-embed-height")return;var h=+e.data.height;if(!h)return;document.querySelectorAll("iframe[src*='testtalkhq.com/embed/']").forEach(function(f){if(!e.source||f.contentWindow===e.source)f.style.height=h+"px"})}window.addEventListener("message",r)})();</script>

Layout Gear for a Straight Fence Line

Fence posts fail from layout as often as from a short hole. Level the first posts, square the corners, snap the line, then cut rails and panels to that line — not to a guess.

Stabila Type 196 48-Inch Box Beam Level

Plumb the first two posts and check the rail before you lock the rest of the run. A walking post is a concrete problem you cannot fix with a longer panel.

View on Amazon →

Klein Tools 935DGGP Digital Angle Gauge

Confirm plumb on a post you cannot sight from both sides, and check rail pitch on a slope. Magnetic base parks on a steel post or a square.

View on Amazon →

Swanson TA122 16 by 24 inch aluminum rafter square

Swanson TA122 Aluminum Rafter Square 16×24

Square the corner posts, mark rail cuts, and keep the first bay from racking the whole line. Same square you will use on gates and braces.

View on Amazon →

TAJIMA Chalk-Rite CR301JF

Snap the fence line after the end posts are set so every hole sits on the same string. Better than walking a tape from a crooked first bay.

View on Amazon →

DEWALT DWE575 7-1/4-Inch Circular Saw

Cut rails and panels to the actual opening, not the plan spacing. Crowns, gates, and the last bay always need a real measurement.

View on Amazon →

As an Amazon Associate, TestTalkHQ earns from qualifying purchases. Product links are from the live TestTalkHQ affiliate CSV only.

How to Use This Fence Post Spacing Calculator

Pick the fence that is actually going in. Measure height above grade and the straight run between ends or corners. Leave preferred on-center blank to use the recommended maximum, or type your panel module (6 ft, 8 ft) and let the tool cap it if wind and height say it is too wide. Enter the hole you will dig, or start from the suggested diameter and depth, then add a gravel bed if you are using one.

posts = ceil(run ÷ working spacing) + 1
actual OC = run ÷ (posts − 1)
concrete/hole (cu ft) = max(0, (A_hole − A_post) × concrete depth) ÷ 1728
60 lb bags = ceil(total cu ft ÷ 0.45) 80 lb bags = ceil(total cu ft ÷ 0.60)

Worked example 100 ft privacy run, 6 ft high, sheltered, no preferred spacing, 4×4 in a 12" × 36" hole with 4" gravel.
Recommended max = 8 ft. posts = ceil(100 ÷ 8) + 1 = 14 posts. Actual OC = 100 ÷ 13 ≈ 7.69 ft.
Concrete depth = 36 − 4 = 32 in. Cylinder minus 3.5" square post, × 14 holes, then bags at 0.45 / 0.60 cu ft.

Gate posts, corner braces, and a change of direction are extra posts on top of this count. Full walkthrough: spacing and concrete guide. If an existing line is leaning or heaving: troubleshooting.

What This Number Is (and Is Not)

The post count is a fence-line takeoff: how many holes on this run at a working on-center that does not exceed the recommended max for type, height, and wind. The bag counts are the hole cylinder minus the post, below the gravel, using 0.45 cu ft per 60 lb bag and 0.60 cu ft per 80 lb bag.

It is not the deck post spacing calculator. Deck posts are sized from IRC beam tables so a beam can span between them. Fence posts hold infill and wind, not a deck beam. Do not mix the two lookups. Other pours (pads, slabs) belong in the concrete volume calculator.

Gate posts are a different job. A swinging gate puts torsion and a point load on two posts. Use a larger post, a deeper hole, and more concrete — or a listed gate-post kit — then add those two posts on top of the line-post count.

Fence Post Spacing FAQ

Is this the same as deck post spacing?

No. Deck post spacing comes from IRC Table R507.5(1) (maximum beam span, labeled as on-center posts). This calculator is a fence-line rule of thumb plus hole concrete. Use the deck post spacing calculator for a deck beam.

Why did my 8 ft panel get capped at 6 ft?

Privacy over 6 ft, picket over 4 ft, or open/high wind drops the recommended maximum. The run uses the safer max so panels do not sag and posts do not take a sail they were not spaced for. Details: guide.

Do I have to use concrete?

No. Concrete, gravel, and packed dirt each win in different soil and climate. This widget sizes a concrete (and gravel bed) takeoff if that is the method you picked. Comparison: which setting method to use.

Why is suggested depth deeper than one-third of the height?

Suggested depth is the maximum of 24", the frost-climate minimum, and height ÷ 3. In a moderate or deep frost climate the frost number wins. Verify the adopted frost line locally.

Are corners and gates included?

A corner is already a shared end post if you run each stretch separately and do not double-count the corner. Gate posts are extra. Add braces and latch posts after you have the line-post count.

Fence Post Spacing & Concrete Calculator